High Voltage Compact Capacitor for Implantable Defibrillator: Worldwide, sudden cardiac arrest is a major health problem. The use of Implantable Cardioverter Defibrillators (ICD) has become an increasingly accepted treatment option, one that could save thousands of heart attack patients annually. With the increase in acceptance of these devices, the drive for improvement of function and materials has intensified. One of the most critical and vital components of the ICD device is a high-voltage capacitor. The function of the capacitor is to store energy over a period of seconds and deliver it to the heart over a period of a few milliseconds. The overall goal of the proposed project is to develop an integrated and unitized (all elements in intimate contact), miniaturized, and all-solid high-voltage capacitor for the next generation of implantable defibrillators. The all-solid high-voltage capacitor is attractive because it can store several times as much energy as a conventional electrolytic capacitor, while retaining the ability to deliver that energy at high discharge rates. It will also allow the stacking of multi-cell units in series in the same package, something not possible in the case of the liquid electrolyte, which requires complicated packaging. This will reduce the number of required capacitors inside the ICD to two, reduce the ICD weight and volume by replacing liquid electrolyte with solid electrolyte, permit use of a bipolar multi-cell series design to achieve high voltages, and, eliminate any possibility of shunt currents and electrolyte leakage, thereby enhancing reliability and safety. The feasibility to develop an advanced miniaturized and all-solid high-voltage capacitor for the next generation of implantable defibrillators was demonstrated in Phase I. Improved tantalum anode formation processes enabled us to form anode components successfully at high voltages up to 350 V, which lead us to believe that even higher voltage can be achieved. During this Phase II program, it is proposed to build full-size 700-V stacks to be studied under long-term and accelerated test conditions. Based on the Phase I results, the technical approach for the Phase II product development program will include 1) further optimization of the tantalum anode structure b) fabricate final cell stacks, evaluate capacitor housings, encapsulation materials, and procedures, b) perform long-term stability and biocompatibility tests, and to, c) Study and select sterilization and packaging options. The successful completion of the Phase II project will result in a miniaturized capacitor and a method of fabricating a novel all-solid capacitor which will have applications for ICDs. PUBLIC HEALTH RELEVANCE: The use of Implantable Cardioverter Defibrillators (ICD) has become an increasingly accepted treatment option, one that could save thousands of heart attack patients annually. There is critical need for reduced size, high energy density capacitor for the ICD. Substantial reduction in the volume and consequently weight of the capacitor inside the ICD would represent a significant product improvement ICD resulting in many advantages for the patients.